The long range objective for this research is to develop model procedures for the examination of pesticides for their potential to impair biochemical, neurological and behavioral development; and to relate these aspects of development to each other and to the mechanisms by which pesticide agents act. Bidrin, a widely used organophosphorus pesticide, will be administered to mice during one of several periods of development. Some groups will be treated prenatally (via an injection of the mother) throughout organogenesis. Others will be treated from birth to weaning and still others during one of three, shorter, postnatal periods that were selected to correlate with specific aspects of neurological development. Prenatally treated offspring will be tested during early reflex development and the sequential development of their responses to reflex-eliciting stimuli will be compared to that of vehicle-injected controls. At age six weeks, prenatally- and postnatally-treated mice will be tested in a series of simple and complex behavioral tasks to determine whether Bidrin treatment has a long-term effect. Other mice will be used to examine neurological and biochemical effects of perinatal Bidrin treatment. The results of behavioral experiments will be compared with the neurological and biochemical data generated in the present research and in experiments that are already in progress. The question of mechanism of action will be examined by combining Bidrin treatment with administration of drugs that interact with organophosphorus compounds.